Really? I dunno, Hammer and Killian are two entirely different personalities. Killian was very insistent, serious, quietly menacing. Hammer is a laid-back fun-loving guy who was played for laughs as a loser who could never get anything right. Even if he had any interest in taking over AIM after Killian's death (and why would he, if it looks like AIM as a company/enterprise is dead in the water at the end of IM3?), I strongly doubt any of the Extremis soldiers would ever give him their trust, loyalty or respect.

I got a totally different impression. That was not Hammer's personality at all (well, except the loser unable to get anything right aspect). He ACTED laid back in an attempt to impersonate Stark's play boy personality. I think we see a much more real Hammer in those moments: someone who thinks he's owed something and who sees Stark as in his way. Kinda like a kid who is part of the in crowd but desperate to be top dog. They play the part to fit in, but just underneath the surface sits a lot of resentment and they would back stab and claw their way back to the top.

I would describe quite a few of my friends as being laid-back and fun loving. It's hard to imagine any of them willing to break an attempted murderer out of jail so that they could embarrass a peer on the national stage. If anything, that comes off as more obsessive and competitive. Mimicking Stark is an extension of that. For me, personally, that is what made Rockwell so fun to watch in the role. It's like an extended and purposefully terrible RDJ impersonation that Hammer is trying so hard to get to work for him when that is just not who he is at all.